Reciprocating compressor and refrigerating apparatus having the same

ABSTRACT

Disclosed are a reciprocating compressor and a refrigerating apparatus having the same, a ball bearing ( 300 ) can be easily stably installed between thrust surfaces ( 213, 227 ) of a cylinder block ( 210 ) and a crank shaft ( 220 ) so as to enhance efficiency of the compressor. Also, a ball bearing ( 300 ) can be installed by being inserted into thrust surfaces ( 213, 227 ) so to shorten a moment arm that much, thereby decreasing a frictional loss at a journal bearing surface ( 215 ), resulting in an energy efficiency of the reciprocating compressor and the refrigerating apparatus having the same. In addition, as an oil hole ( 226   c ) of the crank shaft ( 220 ) is veiled by the journal bearing surface ( 215 ) of the cylinder block ( 210 ), even if a ball bearing ( 300 ) is employed, oil leaked between the thrust surfaces ( 213, 227 ) can be reduced, thereby further enhancing the efficiency of the compressor and the refrigerating apparatus having the same.

TECHNICAL FIELD

The present invention relates to a reciprocating compressor and a refrigerating apparatus having the same, and more particularly, a reciprocating compressor having a ball bearing installed between thrust surfaces of a cylinder block and a crank shaft, and a refrigerating apparatus having the same.

BACKGROUND ART

In general, a hermetic compressor is a compressor provided with a motor unit disposed in a hermetic container for generating a driving force, and a compression unit operated by receiving the driving force from the motor unit. The hermetic compressors may be categorized into a reciprocating type, a rotary type, a vane type and a scroll type according to the compression mechanism with respect to a refrigerant as a compressible fluid.

The reciprocating compressor is configured such that a crank shaft is coupled to a rotor of a motor unit, a connecting rod is coupled to the crankshaft of the motor unit and a piston is coupled to the connecting rod, so that the piston linearly reciprocates within a cylinder to thereby compress a refrigerant.

The reciprocating compressor is configured such that a shaft portion of a crank shaft is inserted into a cylinder block to be supported in a radial direction and simultaneously an eccentric mass portion is laid on the cylinder block to be supported in a shaft direction as well, thereby forming a journal bearing surface and a thrust bearing surface between the crank shaft and the cylinder block. Hence, how to reduce the frictional loss between the crank shaft and the cylinder block as much as possible acts as an important factor on enhancing energy efficiency of the compressor. To this end, an oil passage is formed at the crank shaft so that oil pumped from an oil feeder can evenly be supplied to each bearing surface via the oil passage.

However, the related art reciprocating compressor has limitation on the reduction of frictional loss due to the surface-contact between the thrust surfaces. Taking into account of this, a technology has recently been proposed in which separate bearings such as ball bearings are installed such that the thrust surfaces are point-contactable with each other.

DISCLOSURE OF INVENTION Technical Problem

However, in the related art reciprocating compressor, if at least part of a bearing installed between thrust surfaces of the cylinder block and the crank shaft moves in a radial direction, an assembly operation may not easily be done or the bearing may be slipped out of its original position while the compressor is driven, thereby interfering with the driving or crushing with the crank shaft and the like, causing noise or damage.

Furthermore, as a separate bearing such as a ball bearing is installed between the thrust surfaces, an interval between the thrust surfaces becomes wider by the height of the bearing, which increases moment and accordingly lowers the compressor efficiency. In addition, oil sucked up via the oil passage is excessively discharged via the ball bearing. Consequently, the oil may not be sucked up to the upper end of the crank shaft to thereby cause a drastic frictional loss with the connecting rod, thereby lowering the compressor efficiency.

Therefore, an object of the present invention is to provide a reciprocating compressor capable of facilitating assembly when installing a ball bearing between the thrust surfaces and also ensuring a stable operation, and a refrigerating apparatus having the same.

Another object of the present invention is to provide a reciprocating compressor capable of reducing a frictional loss in a shaft direction between the crank shaft and the cylinder block by virtue of installation of a bearing assembly such as a ball bearing between thrust surfaces, and simultaneously enhancing efficiency by reducing moment due to a gas force within the cylinder and allowing a smooth supply of oil up to the cam portion, and a refrigerating apparatus having the same.

Solution to Problem

To achieve those objects of the present invention, there is provided a reciprocating compressor including a cylinder block provided with a shaft bearing hole to define a journal bearing surface and having a thrust surface on an upper end of the shaft bearing hole, a crank shaft provided with a plate-shaped extending portion extending wider than the shaft bearing hole of the cylinder block, a lower surface of the plate-shaped extending portion defining a thrust surface conformable to the thrust surface of the cylinder block, and a bearing assembly disposed between the thrust surface of the cylinder block and the thrust surface of the crank shaft, the thrust surfaces facing each other, and support the crank shaft in the shaft direction with respect to the cylinder block, wherein at least one of the thrust surface of the cylinder block and thrust surface of the crank shaft is provided with a bearing locking portion for locking at least part of the bearing assembly in the radial direction.

In another aspect of the present invention, there is provided a reciprocating compressor in which a crank shaft for transferring a rotational force is supported by a cylinder block in a radial direction and a shaft direction, a connecting rod is coupled to the crank shaft to convert a rotary motion into a linear motion, and a piston coupled to the connecting rod reciprocates within a cylinder to compress a refrigerant, wherein at least one oil passage is formed within the crank shaft, at least one oil groove is formed at an outer circumferential surface of the crank shaft, the oil passage and the oil groove communicating with each other via at least one oil discharge hole and at least one oil introduction hole, wherein the oil introduction hole is formed at an oil groove, of the at least one oil groove, communicated between the thrust surface of the cylinder block and the thrust surface of the crank shaft, at least part of the oil introduction hole being veiled by the journal bearing surface of the cylinder block.

In one aspect of the present invention, there is provided a refrigerating apparatus including, a compressor, a condenser connected to a discharge side of the compressor, an expansion apparatus connected to the condenser, and an evaporator connected to the expansion apparatus and to a suction side of the compressor, wherein the compressor is provided with a bearing assembly for supporting a shaft direction between a cylinder block and a crank shaft, part of the bearing assembly being supported in a shaft direction by being inserted into the crank shaft while the other portion of the bearing assembly being supported in a radial direction by a bearing locking portion provided at the cylinder block, wherein an oil introduction hole for guiding oil from the inside of the crank shaft to the outside thereof is formed to be veiled by a journal bearing surface.

Advantageous Effects of Invention

In the reciprocating compressor in accordance with the present invention and the refrigerating apparatus having the same, a ball bearing can be easily stably installed between thrust surfaces of the cylinder block and the crank shaft so as to enhance efficiency of the compressor. Also, a ball bearing can be installed by being inserted into thrust surfaces so as to shorten a moment arm that much, thereby decreasing a frictional loss at a journal bearing surface, resulting in an energy efficiency of the reciprocating compressor and the refrigerating apparatus having the same. In addition, as the oil introduction hole for guiding oil from the inside of the crank shaft to the outside thereof is veiled by the journal bearing surface of the cylinder block, oil leaked between facing surfaces in the shaft direction can be reduced, which allows an effective lubrication between a cam portion and the connecting rod and simultaneously effective cooling of a motor unit, resulting in further enhancement of the efficiency of the compressor and the refrigerating apparatus having the same.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a longitudinal sectional view showing an exemplary reciprocating compressor according to the present invention;

FIG. 2 is a front view of a crank shaft of FIG. 1;

FIG. 3 is a perspective view of a cylinder block of FIG. 1;

FIGS. 4 and 5 are a perspective view showing a bearing locking portion of the cylinder block of FIG. 3, wherein FIG. 4 exemplarily shows an annular bearing locking portion and FIG. 5 exemplarily shows an arcuate bearing locking portion;

FIG. 6 is a longitudinal sectional view showing an installed state of ball bearings between the cylinder block and the crank shaft of FIG. 1;

FIG. 7 is a disassembled perspective view showing the cylinder block, the crank shaft and the ball bearing of FIG. 1;

FIG. 8 is a longitudinal sectional view showing an assembled state of the cylinder block, the crank shaft and the ball bearings of FIG. 1;

FIGS. 9 and 10 are graphs showing changes in force applied to each journal bearing surface when installing ball bearings at thrust surfaces in the reciprocating compressor of FIG. 1, wherein FIG. 9 is a graph showing the change in a force applied to the journal bearing surface when the ball bearings are exposed between the thrust surfaces, and FIG. 10 is a graph showing the change in a force applied to the journal bearing surface when the ball bearings are inserted into bearing insertion grooves;

FIG. 11 is a schematic view showing a first oil groove extending from the crank shaft of FIG. 1;

FIG. 12 is a schematic view showing a location of an oil discharge hole of FIG. 1;

FIG. 13 is a longitudinal sectional view showing thrust surfaces of a cylinder block and a crank shaft in accordance with another embodiment of the supporting structure of the ball bearings of FIG. 1;

FIG. 14 is a view taken along the line I-I of FIG. 13;

FIGS. 15 to 17 are longitudinal sectional views showing different embodiments of the supporting structure of the ball bearing according to FIG. 13;

FIG. 18 is a schematic view showing an exemplary refrigerator having the reciprocating compressor according to the present invention;

FIG. 19 is a front view showing another embodiment of the crank shaft of FIG. 1;

FIG. 20 is a longitudinal sectional view showing an assembled state of a cylinder block, a crank shaft and ball bearings in accordance with FIG. 19;

FIG. 21 is a schematic view showing a size (configuration, specification) of a bearing supporting portion of FIG. 19; and

FIG. 22 is a schematic view showing another embodiment of the bearing supporting portion of FIG. 19.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, with reference to the accompanying drawings, description will be made in detail of a reciprocating compressor and a refrigerating apparatus having the same in accordance with embodiments of the present invention.

As shown in FIG. 1, a reciprocating compressor according to the present invention may include a motor unit 100 installed inside a hermetic container 1 and performing a rotation motion, and a compression unit 200 disposed above the motor unit 100 and compressing refrigerant by a rotational force received from the motor unit 100.

The motor unit 100 may be implemented as a constant-speed motor which is rotatable in a forward direction, a constant-speed motor which is rotatable both in forward and reverse direction, or an inverter motor. The motor unit 100 may include a stator 110 elastically installed in the hermetic container 1 with being supported by a cylinder block 210 to be explained later, and a rotor 120 rotatably installed inside the stator 110.

The compression part 200 may include a cylinder block 210 having a cylinder 211 forming a compression space and elastically supported by the hermetic container 1, a crank shaft 220 inserted into the cylinder block 210 to be supported in a radial direction and a shaft direction and coupled to the rotor 120 of the motor unit 100 for transferring a rotational force, a connecting rod 230 rotatably coupled to the crank shaft 220 for converting a rotation motion into a linear motion, a piston 240 rotatably coupled to the connecting rod 230 and linearly reciprocating within the cylinder 211 so as to compress a refrigerant, a valve assembly 250 coupled to an end of the cylinder block 210 and having a suction valve and a discharge valve, a suction muffler 260 coupled to a suction side of the valve assembly 250, a discharge cover 270 coupled to accommodate a discharge side of the valve assembly 250, and a discharge muffler 280 communicating with the discharge cover 270 for attenuating discharge noise of a discharged refrigerant.

With the configuration of the reciprocating compressor according to the present invention, when power is applied to the stator 110 of the motor unit 100, the rotor 120 is rotated with the crank shaft 220 by interaction with the stator 110, and the connecting rod 230 coupled to a cam portion 223 of the crank shaft 220 performs an orbiting motion. The piston 240 coupled to the connecting rod 230 then linearly reciprocates within the cylinder 211 to compress a refrigerant and discharges the compressed refrigerant via the discharge cover 270. The refrigerant discharged via the discharge cover 270 then flows into a refrigerating cycle via the discharge muffler 280. The series of processes are repeated.

The crank shaft 220 is rotated so that the oil feeder O installed at a lower end of the crank shaft 220 pumps up oil contained in an oil storing unit of the hermetic container 1. Such oil is sucked up via the oil passage of the crank shaft 220 so as to be supported to each bearing surface. Here, the oil is partially dispersed at the upper end of the crank shaft 220 so as to cool the motor unit 100.

Hereinafter, a construction of a crank shaft for pumping up oil stored in an oil storing unit of the hermetic container 1 will be described.

That is, as shown in FIG. 2, the crank shaft 220 may include a shaft portion 221 coupled to the rotor 120 and inserted into a shaft bearing hole 212 of the cylinder block 210 so as to be supported by the cylinder block 210 in a radial direction, an eccentric mass portion 222 eccentrically formed at an upper end of the shaft portion 221 in a fan-shape or a shape of an eccentric circular flange so as to define a plate-shaped extending portion, and a cam portion 223 formed on an upper surface of the eccentric mass portion 222 to be eccentric from the shaft portion 221 and allowing the connecting rod 230 to be rotatably inserted thereinto.

The shaft portion 221 may be provided with a first journal bearing surface 229 a and a second journal bearing surface 229 b formed at an outer circumferential surface thereof corresponding to a journal bearing surface 215 of the shaft bearing hole 212 with a predetermined interval therebetween. A first oil passage 225 a may be formed in a shaft direction from a lower end of the shaft portion 221 to the upper end thereof or formed within the defined area to be slightly inclined in the shaft direction, and a second oil passage 225 b may be formed in the shaft direction from an upper end of the cam portion 223 to an upper side of the shaft portion 221 with a predetermined depth. The first oil passage 225 a and the second oil passage 225 b may not be communicated with each other.

A first oil discharge hole 226 a for inducing oil toward the second journal bearing surface 229 b of the crank shaft 220 may be formed at a middle portion of the first oil passage 225 a, namely, at a portion corresponding to a lower portion of the journal bearing surface 215 of the shaft bearing hole 212. A first oil groove 226 b with a predetermined inclination angle may be spirally formed from the first oil discharge hole 226 a by a predetermined height, namely, up to almost end of the shaft bearing hole 212. An oil introduction hole 226 c communicating with the second oil passage 225 b may be formed at an end of the first oil groove 226 b, and a second oil discharge hole 226 d for inducing oil sucked up via the second oil passage 225 b to an outer circumferential surface may be formed at a middle of the second oil passage 225 b, namely, at a portion coupled to the connecting rod 230. A second oil groove 226 e having a preset inclination angle may be spirally formed between the second oil discharge hole 226 d and an upper end of the cam portion 223.

With such configuration, oil pumped up by the oil feeder O is sucked up via the first oil passage 225 a, and partially guided into the first oil groove 226 b via the first oil discharge hole 226 a. The oil guided into the oil groove 226 b then flows up along the first oil groove 226 b to sequentially lubricate the first journal bearing surface 229 b and a first journal bearing surface 229 a of the crank shaft 220.

The oil having lubricated the journal bearing surfaces 229 a and 229 b is introduced into the second oil passage 225 b via the oil discharge hole 226 c, so as to be sucked up again. Part of the oil flows into the second oil groove 226 e via the second oil discharge hole 226 d so as to lubricate the cam portion 223 of the crank shaft 220.

Here, the crank shaft may be rotated with being inserted into the shaft bearing hole of the cylinder block, thereby being supported in a radial direction and simultaneously in a shaft direction. However, the crank shaft is coupled to the rotor as mentioned above, so the weight of the crank shaft and the weight of the rotor increase a load in a shaft direction, which may aggregate a frictional loss with the cylinder block. Taking this into account, an approach may be considered in which a point-contactable bearing, such as a ball bearing, may be installed between a thrust surface of the cylinder block and a thrust surface of the crank shaft so as to reduce the frictional loss in the shaft direction.

To this end, as shown in FIGS. 1 to 6, the shaft bearing hole 212, which forms a journal bearing surface so that the crank shaft 220 is inserted therein so as to be supported in the radial direction, may be formed at a center of the cylinder block 210. A thrust surface 213 may be formed at a periphery of an upper end of the shaft bearing hole 212 and thus a ball bearing assembly (hereinafter, referred to as ball bearing) for supporting the crank shaft 220 in the shaft direction can be laid on the thrust surface 213. A bearing locking portion 214 with a preset height may be formed at an edge of the thrust surface 213 so as to support a lower washer (or a second washer) 332 to be explained later. Here, a thrust surface 227 of the crank shaft 220 conformable to the thrust surface 213 of the cylinder block 210 may be formed to be flat.

The bearing locking portion 214 may have a height lower than a height of the ball bearing 300 in the shaft direction. For example, an interval between an end surface of the bearing locking portion 214 and the thrust surface 227 of the crank shaft 220 may be lower then the shaft-directional height of the ball bearing 300. Also, the height of the bearing locking portion 214 may not be greater than a thickness of the lower washer 332 to be explained later.

The bearing locking portion 214 may be formed in an annular shape as shown in FIG. 4; alternatively, it may be formed in any shape capable of locking the lower washer 332 in the radial direction, as shown in FIG. 5, for example, in a shape of having at least three arcuate protrusions along a circumferential direction. Although not shown, the bearing locking portion 214 may be formed to be contactable with an inner circumferential surface of the lower washer 332.

As another embodiment, although not shown, the bearing locking portion 214 may be formed at the thrust surface 227 of the crank shaft 220, namely, a thrust surface 227 of the eccentric mass portion 222.

Still referring to FIGS. 1 to 7, each ball bearing 300 may include a ball cage 310 in an annular shape, at least three balls 320 all rotatably coupled to the ball cage 310, and washers 331 and 332 installed to be contactable with both sides of the balls 320 in a shaft direction. The washers may not be the essential components but be installed at any one side.

The diameter of each ball 320 may be greater than a thickness of the ball cage 310. The balls 320 may be fixedly coupled to the ball cage 310.

The washers 331 and 332 may be classified into an upper washer (or first washer) 331 and a lower washer (or second washer) 332 based upon the balls 320. The upper and lower washers 331 and 332 may be preferably installed to be supported by the cylinder block 210 and the crank shaft 220, respectively, in the radial direction, which allows a smooth bearing action. That is, the upper washer 331 may be inserted into an outer circumferential surface of the crank shaft 220 together with the ball cage 310 to be supported in the radial direction, while the lower washer 332 may be closely adhered to an inner circumferential surface of the bearing locking portion 214 provided at the thrust surface 213 of the cylinder block 210 so as to be locked in the radial direction. The bearing locking portion 214 may be formed at a periphery of the shaft bearing hole 212 on the thrust surface 213 of the cylinder block 210 such that its outer circumferential surface contacts an inner circumferential surface of the lower washer 332.

As such, the installation of the ball bearing 300 between the cylinder block 210 and the crank shaft 220 can remarkably reduce the frictional loss in the shaft direction between the cylinder block 210 and the crank shaft 220, thereby enhancing energy efficiency of the compressor. Also, as the ball bearing 300, especially, the lower washer 332 is locked by the bearing locking portion 214 of the cylinder block 210 in the radial direction, the lower washer 332 can always stay at its original position, thereby allowing a stable operation of the ball bearing 300.

Another embodiment of a reciprocating compressor according to the present invention is as follows. That is, in case of installing such ball bearing between thrust surfaces, oil leakage in a thrusting direction may be caused due to the characteristic of the ball bearing. Accordingly, oil guided from the middle of the crank shaft to the outside of the crank shaft cannot be sucked up any more, whereby oil may not be supplied to the bearing surfaces with the connecting rod, especially, a sleeve or not be sucked up to the upper end. Further, a moment arm may become as long as the height of the ball bearing, thereby lowering the compressor efficiency.

Accordingly, the ball bearing is allowed to be inserted into the cylinder block or the crank shaft to reduce an interval between the crank shaft and the cylinder block, so as to minimize the oil leakage at the middle of the crank shaft due to the oil discharge hole of the crank shaft being shielded by the journal bearing surface and simultaneously reduce the length of the moment arm, thereby enhancing the compressor efficiency.

To this end, as shown in FIGS. 7 and 8, bearing insertion grooves 228 in which the ball bearings 300 can be inserted may be formed. Preferably, a shaft-directional height d of the bearing insertion groove 228 may not be higher than the shaft-directional height h of the ball bearing 300. For example, the shaft-directional height d of bearing insertion groove 228 may not be lower than the half of the shaft-directional height h of the ball bearing 300, thereby preventing oil leakage between the thrust surfaces 213 and 227 of the cylinder block 210 and the crank shaft 220. In other words, the shaft-directional height (i.e., depth) d of the bearing insertion groove 228, as shown in FIG. 8, may be preferably formed such that an interval t between the cylinder block 210 and the crank shaft 220 (i.e., an interval between the thrust surfaces) in the shaft direction cannot be greater than the shaft-directional height h of the ball bearing 300.

Although not shown, the bearing insertion groove 228 may be formed at the thrust surface 213 of the cylinder block 210 or formed at both the thrust surface 213 of the cylinder block 210 and the thrust surface 227 of the crank shaft 220.

Referring to FIG. 8, as each ball bearing 300 is installed by being inserted into the bearing insertion groove 228 provided at the crank shaft 220, the interval t between the cylinder block 210 and the crank shaft 220 may be shorter than the height h of the ball bearing 300 to thereby shorten the length of the moment arm. Accordingly, respective forces F2 and F3 applied to the first journal bearing surface 229 a and the second journal bearing surface 229 b are decreased, and the frictional losses at the journal bearing surfaces 229 a and 229 b are accordingly decreased so much, thereby enhancing the energy efficiency of the compressor. For instance, a distance L1 from the center of the cam portion 223 to the journal bearing surface, namely, to the center of the first journal bearing surface 229 a for supporting a repulsive force against a gas force applied to the cam portion 223 becomes shorter, while a distance L2 from the first journal bearing surface 229 a to the second journal bearing surface 229 b becomes longer, so that the forces F2 and F3 respectively applied to the first journal bearing surface 229 a and the second journal bearing surface 229 b can be reduced. In the drawing, F1 denotes a gas force applied to the cam portion 223, and the gas force may depend on an internal pressure and a sectional area of a cylinder.

FIGS. 9 and 10 show graphs showing the changes in the forces applied to each journal bearing surface respectively in case where an interval between the cam portion and the first journal bearing surface is reduced by approximately 5 mm and case where the interval between the first journal bearing surface and the second journal bearing surface is reduced by approximately 5 mm in the configuration that the ball bearings are installed between the cylinder block and the crank shaft by being inserted into the crank shaft.

That is, in case where the ball bearings, as in the related art, are installed at the facing surfaces between the cylinder block and the crank shaft to have a preset height, as shown in FIG. 9, a force F1 applied to the cam portion conformable to a gas force is approximately 600N. In this case, the force F2 applied to the first journal bearing surface is approximately 1000N and the force F3 applied to the second journal bearing surface is approximately 300N. However, as shown in the present invention, in case where the ball bearings are inserted into the cylinder block 210 or the crank shaft 220, as shown in FIG. 10, when the force F1 applied to the cam portion 223 is approximately 600N, the force F2 applied to the first journal bearing surface is approximately 850N and the force F3 applied to the second journal bearing surface is approximately 150N.

Consequently, when the bearing insertion groove is formed at the thrust surface of the crank shaft and the ball bearing is partially inserted into the bearing insertion groove, approximately 20% of the force applied to the first journal bearing surface is reduced and approximately 50% of the force applied to the second journal bearing surface is reduced, so the torque required for a motor can be reduced, thereby obtaining an effect of enhanced energy efficiency EER of the compressor.

In the meantime, the oil introduction hole 226 c may preferably be formed at a position where at least part thereof can be veiled by the journal bearing surface 215 of the cylinder block 210, thereby minimizing oil guided via the first oil groove 226 b from being leaked, between the cylinder block 210 and the crank shaft 220. Therefore, the lubrication performance at the cam portion can be improved so as to further enhance the compressor efficiency.

For instance, as shown in FIG. 11, the first oil groove 226 b of the crank shaft 220 may be spirally formed to have a preset inclination angle, and the spiral angle may be greater or smaller than about 60°, namely, in the range of 45° to 90°. This is intended to form the oil introduction hole 226 c at a position with a narrower angle than a typical spiral angle. Although not shown, the length of the first oil groove 226 b may be shortened while maintaining the inclination angle thereof as same as that in the related art so that at least part of the oil discharge hole can be veiled by the upper portion of the journal bearing surface.

The first oil groove 226 b may be formed to have a single inclination angle; but in some cases, it may have a plurality of inclination angles. This is to allow a large amount of oil to be stored at a portion of the journal bearing surface where a load is concentrated, namely, at the first journal bearing surface 229 a adjacent to the cam portion 223.

For example, as shown in FIG. 11, if the first oil groove 226 b has a plurality of inclination angle, a lower groove g1 may be formed, for example, with an inclination angle α1 of 45° at a lower side of the first oil groove 226 b, namely, up to a preset height from the first oil discharge hole 226 a, and an upper groove g2 may be formed, for example, with an inclination angle α of 30° from the preset height up to the oil introduction hole 226 c.

Meanwhile, in order for part of oil sucked up along the first oil groove 226 b to stay at an upper end of the first oil groove 226 b, namely, at the periphery of the oil introduction hole 226 c, a corner between the journal bearing surface and the thrust surface of the cylinder block 210 may be cut off so as to define a chamfer or a round oil pocket 216. Even in this case, as shown in FIG. 12, in order for part of the oil introduction hole 226 c to be veiled by the journal bearing surface of the cylinder block 210, the lowermost point of the oil introduction hole 226 c may preferably be formed to be lower than the lowermost point of the oil pocket 216 at least by a preset height difference Δh, namely, the oil introduction hole 216 may be preferably formed such that the longest distance L3 from the lower surface of the eccentric mass portion 222 of the crank shaft 220 may be formed not to be shorter than the shortest distance L4 from the lower surface to the journal bearing surface 215 of the cylinder block 210. Such formation can reduce oil leakage between the cylinder block 210 and the crank shaft 220.

Hence, as at least part of the oil introduction hole 226 c is formed to be veiled by the journal bearing surface 215 of the cylinder block 210, even if the ball bearing 300 from which oil may be leaked is installed at the thrust surface, oil guided via the first oil groove 226 b can be minimized from being leaked between the cylinder block 210 and the crank shaft 220. Accordingly, the oil guided via the first oil groove 226 b is led toward the second oil passage 225 b via the oil introduction hole 226 c, thus allowing effective lubrication between the cam portion 223 and the connecting rod 230 and simultaneously smooth suction of oil up to an upper end of the crank shaft 220, so as to effectively cool the motor unit 200, resulting in further enhancement of the compressor efficiency.

In the meantime, another embodiment of a structure of supporting a ball bearing of the reciprocating compressor according to the present invention will be described.

That is, the previous embodiment has illustrated that the ball bearings 300 are inserted into the bearing insertion grooves 228 located at the lower surface of the eccentric mass portion 222; however, this embodiment illustrates that the ball bearing 300 may be installed at each of the thrust surface of the crank shaft and the thrust surface of the cylinder block.

For instance, as shown in FIGS. 13 and 14, bearing insertion grooves 218 and 228 may be formed at the thrust surface 213 of the cylinder block 210 and the thrust surface 217 of the crank shaft 220 such that the balls 320 of the ball bearing 300 can be partially inserted therebetween. The bearing insertion grooves 218 and 228 may be formed to be annular such that the balls 320 of the ball bearing 300 can be slid in a circumferential direction, and preferably have a depth less than at least 50% of a diameter of the ball 320, considering a thickness of the ball cage 310.

In the configuration of the ball bearing 300, an outer circumferential surface of each ball 320 may have the same curvature as that of an inner circumferential surface of the bearing insertion groove 218 and 228 so as to be linearly contactable with each other.

Here, washers 331 and 332 each having an arcuate section, as shown in FIG. 15, may be located at inner circumferential surfaces of the bearing insertion grooves 218 and 228. The washers 331 and 332 may preferably be formed of a material with abrasion resistance superior to that of the cylinder block 210 or the crank shaft 220.

As shown in FIG. 16, the bearing insertion grooves 218 and 228 each may be formed in a square shape as in the previous embodiment, and washers 331 and 332, each having an outer circumferential surface in a square shape and an inner circumferential surface in an arcuate sectional section with the same curvature to the ball 320, may be inserted into the bearing insertion grooves 218 and 228, which renders the washers 331 and 332 to be easily assembled. Also, as shown in FIG. 17, the bearing insertion grooves 218 and 228 each may be formed in a square shape, as in the previous embodiment, and washers 331 and 332 each in a shape of annular plate may be inserted into the bearing insertion grooves 218 and 228 for installation, which renders the washers 331 and 332 to be easily fabricated.

Even in case where the bearing insertion grooves 218 and 228 are formed between the cylinder block 210 and the crank shaft 220 so that each ball 320 of the ball bearing 310 can be partially inserted, the height of the ball bearing 300 may be lowered by a preset level, as aforementioned, so as to reduce the amount of oil leaked between the cylinder block 210 and the crank shaft 220 and simultaneously reduce frictional loss due to a gas force, thereby enhancing the energy efficiency of the compressor.

Meanwhile, when the reciprocating compressor according to the present invention is applied to a refrigerating apparatus, the performance of the refrigerating apparatus can be improved.

For example, as shown in FIG. 18, in a refrigerating apparatus 700 having a refrigerant compression type refrigerating cycle having a compressor, a condenser, an expansion apparatus and an evaporator, a reciprocating compressor C, in which point-contactable bearings such as ball bearings are inserted into bearing insertion grooves located at the thrust surfaces, as aforesaid, is installed at a main board 710 for controlling an overall operation of the refrigerating apparatus within the refrigerating apparatus 700. The reciprocating compressor C may be disposed at a position where the oil hole for communicating an oil groove with an oil passage of a crank shaft is shielded by a journal bearing surface. Consequently, the refrigerating apparatus can achieve the effects aforesaid in the description of the reciprocating compressor and the performance of the refrigerating apparatus having the reciprocating compressor can be improved.

Another embodiment of the present invention will now be described.

That is, in the previous embodiments, the bearing insertion groove is formed at the thrust surface of the cylinder block or the thrust surface of the crank shaft and the bearing assembly is inserted in the bearing insertion groove, so as to retain a short distance between the thrust surfaces of the cylinder block and the crank shaft. However, this embodiment illustrates the following structure. That is, in case where the bearing assembly is exposedly installed at the thrust surface of the cylinder block or the thrust surface of the crank shaft other than by being inserted therein, instead of minimizing the height of the bearing assembly, the bearing assembly is allowed to be kept staying at its original location without being separated between the thrust surfaces, thereby reducing the frictional loss between the thrust surfaces.

For example, if a bearing with a preset height, such as a ball bearing, is exposedly disposed between the thrust surfaces of the cylinder block 210 and the crank shaft 220, an interval between the thrust surfaces becomes wider and additionally the wider interval renders oil sucked up via the first oil groove 226 b flow out toward the thrust surfaces without flowing toward the oil introduction hole 226 c, thereby lowering the compressor efficiency. Therefore, when installing the ball bearing between the cylinder block and the crank shaft, the diameter of each ball of the ball bearing can be fabricated as small as possible, to prevent the interval between the thrust surfaces from being excessively increased due to the installation of the ball bearing.

However, if the diameter of the ball bearing becomes too short and the ball bearing moves in a radial direction, the balls of the ball bearing are slipped out of the oil pocket between the thrust surface and the journal bearing surface of the cylinder block, thereby possibly causing the ball bearing not to function as a bearing.

To consider this problem, as shown in FIGS. 19 and 20, a bearing supporting portion 224 for supporting the ball bearing 300 in a radial direction should be formed at an outer circumferential surface of the crank shaft 220 facing the inner circumferential surface of the ball bearing 300, or, although not shown, the ball cage 310 of the ball bearing 300 should extend in its inner circumferential surface. For the latter, if the ball cage 310 is thinly fabricated, as the width thereof becomes wider, the intensity of the ball cage 310 becomes weaker, thereby increasing the chance of damage or deformation of the ball cage 310. Accordingly, each ball 320 coupled to the ball cage 310 may not smoothly rotate, thus drastically lowering the bearing performance. Therefore, in order to render the balls 320 stay at proper positions, namely, position not to be slipped out of the oil pockets 216 without widening the width of the ball cage 310, the bearing supporting portion 224, as similar to the former, may preferably be formed at the outer circumferential surface of the crank shaft 220. Further, in any manner of increasing the intensity of the ball cage 310, it may also be possible to widen the width of the ball cage 310.

FIG. 21 shows an example in which the bearing supporting portion is protruded from the outer circumferential surface of the crank shaft 220 to have a preset thickness in a stepped state. As shown in FIG. 21, the bearing supporting portion 224 may extend between the first journal bearing surface 229 a and the thrust surface, namely, from the thrust surface in a shaft direction, so as to be in the stepped state. The bearing supporting portion 224 may preferably be formed such that a distance B from a shaft center of the crank shaft 220 to the center of the ball 320 may not be shorter than a distance CB1 from the shaft center of the crank shaft 220 to the lowermost point of the oil pocket 216, more particularly, a distance D from the shaft center of the crank shaft 220 to an outer circumferential surface of the bearing supporting portion 224. Such formation can prevent the ball 320 from being slipped out of the oil pocket 216.

The bearing supporting portion 224 may preferably be formed to have a length long enough that the ball cage 310 cannot be slipped out of a lower side of the bearing supporting portion 224, namely, toward the first journal bearing surface 229 a. To this end, a height H1 of the bearing supporting portion 224 may be higher than a distance HCU from a lower surface of the eccentric mass portion 222 to an upper surface of the ball cage 310. That is, the height of the bearing supporting portion 224 may not be lower than the distance HCU from the thrust surface of the eccentric mass portion 222 to the upper surface of the ball cage 310 and not lower than a distance HCL from the thrust surface of the eccentric portion 222 to the lower surface of the ball cage 310, thereby preventing the ball cage 310 from being slipped out of the lower side of the bearing supporting portion 224, namely, out of the oil pocket 216.

Washers 331 and 332 for supporting the balls 320 may further be installed at both sides of the ball bearing 310 in the shaft direction. However, the washers 331 and 332 may not be essential components; alternatively, one washer may be installed at one side.

The washers 331 and 332 may be classified into an upper washer (or first washer) 331 and a lower washer 332 based upon the balls 320. The upper and lower washers 331 and 332 may be preferably installed to be supported by the cylinder block 210 and the crank shaft 220, respectively, in the radial direction, which allows a smooth bearing action. The ball cage 310 may be disposed, as aforesaid, such that its inner circumferential surface can be supported by the crank shaft 220. The lower washer 332 may have an outer circumferential surface supported by the bearing locking portion 214 of the cylinder block 210. In this case, a height H2 of the bearing locking portion 214 may be lower than a distance HBL2 from a bottom surface of the thrust surface 213 to the lower surface of the ball cage 310, which allows a stable bearing action of the outer circumferential surface of the ball cage 310 due to unlocked state thereof from the cylinder block 210.

Here, the thickness of each washer 331 and 332 may not preferably be greater than the diameter 320, thereby maintaining a preset level of diameter of the ball 320. For instance, the diameter of the ball 320 may be formed within the range of 1.5-10 times the thickness of the washers 331 and 332 (1.5-10×thickness), thereby maintaining the intensity of the ball 320 in the shaft direction.

In the meantime, as aforementioned, the bearing supporting portion 224 may be integrally formed with the crank shaft 220; in some cases, it may be formed in a form of bush so as to be assembled to the crank shaft 220 by bolts or rivets. Even in this case, the size (configuration) of the bearing supporting portion 224 should be the same to the aforesaid embodiments, so the detailed description thereof will be omitted.

As another embodiment, the ball bearing according to the present invention may have the outer circumferential surface supported by the cylinder block 210 unlike the aforesaid embodiments. To this end, as shown in FIG. 22, the height H2 of the bearing locking portion 214 may be formed higher and the outer circumferential surface of the ball cage 310 is allowed to be supported by the inner circumferential surface of the bearing locking portion 214 in the radial direction.

Even in this case, the inner circumferential surface of the ball cage 310 should not be supported by the outer circumferential surface of the crank shaft 220. If the outer circumferential surface of the ball cage 310 is supported by the cylinder block 210 and the inner circumferential surface thereof is supported by the crank shaft 220, an excessive load is applied to the ball bearing 300 in the radial direction, thereby worrying about the damage or destroy of the ball bearing 300.

Not only when the inner circumferential surface of the ball cage 310 of the ball bearing 300 is supported by the outer circumferential surface of the crank shaft 220, namely, by the outer circumferential surface of the bearing supporting portion 224 of the crank shaft 220, but also when the outer circumferential surface of the ball cage 310 is supported by the inner circumferential surface of the bearing locking portion 214 of the cylinder block 210, a preset interval may preferably be maintained between the ball cage 310 and the surfaces supporting the ball cage 310, thus increasing reliability of the ball bearing 300.

Here, the configuration of the bearing locking portion for allowing the ball cage to be supported by the cylinder block can be obviously understood upon considering the aforesaid example, namely, being supported by the crank shaft. As one example, the height H2 of the bearing locking portion 214 should be higher than at least the height HCL1 from the thrust surface 213 to the lower surface of the ball cage 310.

The reciprocating compressor according to the present invention may have the following operational effects.

That is, the installation of the ball bearing 300 between the thrust surfaces of the cylinder block 310 and the crank shaft 320 can remarkably decrease a frictional loss between the thrust surfaces, thereby improving the energy efficiency of the compressor.

As the bearing supporting portion 224 is formed at the crank shaft 220 so as to reduce the diameter of the ball 320 of the ball bearing 300 and simultaneously support the ball cage 310 in the radial direction, the ball bearing 300 can always be located at its original position, thereby preventing in advance the lowering of the bearing performance. Also, the reduced diameter of the ball 320 may prevent an excessive increase in the interval between the thrust surfaces, thereby preventing an excessive lengthening of the length of the moment arm, resulting in preventing an increase in forces applied respectively to the first journal bearing surface 229 a and the second journal bearing surface 229 b. Hence, the frictional loss at the journal bearing surfaces 229 a and 229 b can be reduced, thereby enhancing the energy efficiency of the compressor.

In the meantime, if the reciprocating compressor according to the present invention is applied to a refrigerating apparatus, as mentioned in the previous embodiment, the performance of the refrigerating apparatus can be improved.

INDUSTRIAL APPLICABILITY

In association with the reciprocating compressor and the refrigerating apparatus having the same according to the present invention, a single type reciprocating compressor having a single cylinder has been illustrated; however, in some cases, the present invention can also be applied to a multi-type reciprocating compressor having many cylinders and a refrigerating apparatus having the same. 

1. A reciprocating compressor comprising: a cylinder block provided with a shaft bearing hole to define a journal bearing surface and having a thrust surface on an upper end of the shaft bearing hole; a crank shaft provided with a plate-shaped extending portion extending wider than the shaft bearing hole of the cylinder block, a lower surface of the plate-shaped extending portion defining a thrust surface conformable to the thrust surface of the cylinder block; and a bearing assembly disposed between the thrust surface of the cylinder block and the thrust surface of the crank shaft, the thrust surfaces facing each other, and support the crank shaft in the shaft direction with respect to the cylinder block, wherein at least one of the thrust surface of the cylinder block and thrust surface of the crank shaft is provided with a bearing locking portion for locking at least part of the bearing assembly in the radial direction.
 2. The compressor of claim 1, wherein the beating locking portion is configured as an annular protrusion to be contactable with an outer circumferential surface or an inner circumferential surface of the bearing assembly, or comprises at least three or more arcuate protrusions along a circumferential direction.
 3. The compressor of claim 1, wherein a bearing insertion groove is formed at least one of the thrust surface of the cylinder block or the thrust surface of the crank shaft so that at least part of the bearing assembly is inserted therein.
 4. The compressor of claim 3, wherein a height of the bearing insertion groove in the shaft direction is defined such that a minimum interval in the shaft direction between the thrust surface of the cylinder block and the thrust surface of the crank shaft is not greater than a height of the bearing assembly in the shaft direction.
 5. The compressor of claim 1, wherein at least one oil passage is formed within the crank shaft, at least one oil groove is formed at an outer circumferential surface of the crank shaft, the oil passage and the oil groove communicating with each other via at least one oil discharge hole and at least one oil introduction hole, wherein the oil introduction hole is formed at an oil groove, of the at least one oil groove, communicated between the thrust surface of the cylinder block and the thrust surface of the crank shaft, at least part of the oil introduction hole being veiled by the journal bearing surface of the cylinder block.
 6. (canceled)
 7. The compressor of claim 5, wherein the oil groove has a plurality of inclination angles, wherein an inclination angle at a portion adjacent to the oil introduction hole, among the plurality of inclination angles, is relatively smaller than an inclination angle at a portion away from the oil introduction hole.
 8. The compressor of claim 5, wherein an edge between the journal bearing surface and the thrust surface of the cylinder block is chamfered or round.
 9. The compressor of claim 5, wherein a bearing insertion groove in which part of the bearing assembly is inserted is formed either at the thrust surface of the crank shaft or at the thrust surface of the cylinder block.
 10. The compressor of claim 1, wherein the bearing assembly comprises a ball cage fotuied in an annular shape with a preset thickness, and at least three balls each having a diameter greater than the thickness of the ball cage and coupled to the ball cage; wherein a bearing insertion groove in which part of the bearing assembly is inserted is formed either at the thrust surface of the crank shaft or at the thrust surface of the cylinder block, a depth of the bearing insertion groove being deep enough that at least part of the ball cage is inserted.
 11. (canceled)
 12. The compressor of claim 10, wherein the bearing assembly comprises a washer in an annular shape fondled at least one of both sides of the balls in the shaft direction to be contactable with the balls, at least one washer being located at an outer periphery of the bearing insertion groove.
 13. The compressor of claim 12, wherein a thickness of the washer located at the outer periphery of the bearing insertion groove is not thinner than a height of the bearing locking portion.
 14. The compressor of claim 1, wherein a thrust surface without the bearing locking portion formed, of the thrust surface of the cylinder block or the thrust surface of the crank shaft, the thrust surfaces facing each other, is formed to be flat.
 15. The compressor of claim 14, wherein the crank shaft is provided with a journal bearing surface inserted into the shaft bearing hole of the cylinder block, wherein a bearing supporting portion greater than an outer diameter of the journal bearing surface is integrally twined or assembled between the journal bearing surface and the plate-shaped extending portion of the crank shaft.
 16. The compressor of claim 14, wherein the bearing supporting portion has a length in the shaft direction which is not longer than the length of the bearing assembly in the shaft direction.
 17. The compressor of claim 14, wherein an oil pocket larger than a diameter of the shaft bearing hole is formed at an edge between the journal bearing surface and a flat surface in the shaft direction of the cylinder block, wherein the bearing supporting portion and the bearing locking portion support the bearing assembly in the radial direction such that a center of the bearing assembly in the shaft direction is located out of the range of the oil pocket.
 18. The compressor of claim 14, wherein the bearing assembly comprises a ball cage formed in an annular shape with a preset thickness, and at least three balls each having a diameter greater than the thickness of the ball cage and coupled to the ball cage.
 19. The compressor of claim 18, wherein washers are provided at both side surfaces of the balls in the shaft direction to be contactable with the balls, each washer being supported by the bearing supporting portion or the bearing locking portion in the radial direction.
 20. (canceled)
 21. A reciprocating compressor in which a crank shaft for transferring a rotational force is supported by a cylinder block in a radial direction and a shaft direction, a connecting rod is coupled to the crank shaft to convert a rotary motion into a linear motion, and a piston coupled to the connecting rod reciprocates within a cylinder to compress a refrigerant, wherein at least one oil passage is formed within the crank shaft, at least one oil groove is formed at an outer circumferential surface of the crank shaft, the oil passage and the oil groove communicating with each other via at least one oil discharge hole and at least one oil introduction hole, wherein the oil introduction hole is formed at an oil groove, of the at least one oil groove, communicated between the thrust surface of the cylinder block and the thrust surface of the crank shaft, at least part of the oil introduction hole being veiled by the journal bearing surface of the cylinder block.
 22. (canceled)
 23. The compressor of claim 21, wherein the oil groove has a plurality of inclination angles, wherein an inclination angle at a portion adjacent to the oil introduction hole, among the plurality of inclination angles, is relatively smaller than an inclination angle at a portion away from the oil introduction hole.
 24. A refrigerating apparatus comprising: a compressor; a condenser connected to a discharge side of the compressor; an expansion apparatus connected to the condenser; and an evaporator connected to the expansion apparatus and to a suction side of the compressor, wherein the compressor is configured according to claim
 1. 